Electronic timer



July 8, 1952 AUDIER 2,602,888

ELECTRONIC TIMER Filed Sept. 4, 1945 VOLTAGE TIME Patented July 8, 1952UNITED STATES PATENT OFFICE ELECTRONIC TIIWERY Mark Audieig Milwaukee,Wis.; assignor t'o' Cutler Hammer, Inc.,-Milwaukee,1Wis.'-,its-corporation of Delaware Application'september 4, 1945 SerialjIN'oI614l',' l'," 4jiv 3. Claims; (Cl. 250%27') This invention. relatesto improvements in electric timing systems of the condenser type.

Condensers have heretofore been employed in timing. systems but not tofull advantage, the prior uses having been such as to necessitate arelatively'large condenser where a substantial time. element is needed.The time element ob tained has been an exponential function of thechange. involtageof the condenser and as a con-' sequence: the condensercapacity has not been employed efficiently.

The present invention has among its objects to provide a system whereinthe condenser is so utilized that the potential change of which timingis a function is linear and whereby the condenser capacity is moreefficiently employed- Another object is to provide a timing system whichis of increased accuracy and which affords with use of a condenser ofgiven capacity a longer timing period.

Another object is to provide a timing system of the condenser typewherein such more advantageous use of the condenser is enabled by areadily accomplished coordination of the condenser and an electron tube.

Another object is toprovidea timingsystem of the characteraforeindicatedwhich aiiords ad-v justment over a wide range of the time elementprovided thereby.

Another object is to provide a timing system having numerousadvantageous applications including timing of circuit commutations formotors andother translating devices.

Other objects and advantages will hereinafter appear.

The invention comprehends a system in which the potential of a circuitelement is :varied substantially linearly as a function of lapse of timefollowing initiation of a given condition of the circuit whereby aneffect is produced upon the circuit as such potential attains a givenvalue. A more specific example is raising linearly with the lapse oftime'the potential of the cathode of an electron tube supplied withenergy byvaryingthe potential of the control electrode of the tube withrespect to the cathodein accordance with the change of the cathodepotential.

The-accompanying drawing is illustrativeof anembodiment of theinvention, it beingunderstood that the embodiment illustratedissusceptible of various modifications without departing; from thescope-of the appended claims. a

Fig. 1 is a connection diagram showing1the timing system applied tocontrol -.of an electric;

motor. and Y 2 Fi'g-e2 isa curve of-the potential of certain elements ofthe system shown in Fig. 1.

The system as shown-in Fig. 1 comprises a 'positive bus bar IIl'and-anegative busbar II of a direct current supply which furnishes electricalenergyto the armature I2 ofa directcu'rrent' motorwhoseshunt fieldwinding I2 m'ay be energized in any suitable "manner;

One terminal ofthe armature'IZ is connected to the bus bar-l0 throughanormally open'main contact I3 of an electromagnetic switch I 3 which isprovided with an energizing winding I 3!? and normallyopen auxiliarycontacts I3"and"f I3 The 7 other "terminal of the armature I2 is con'-'nected through a starting resistor I4 to'the'b us bar I I. The startingresistor I 4 may be short cir cultedby the'normally open contact" I5 ofan electromagnetic switch I 5 which is provided with an energizingwinding I5 Oneterminal-of the winding I 5 is connected to the anode I 6'of an electron tube ISWhlCh also has a cathode I S and acontrolelectrode-I62 A highva'cuum electron tube ITis provided-with a cathodeIl an, anode IT, and a'control electrode I1; The cathode'll is connectedthrough a resistor "I 8 to'the bus bar I I ,The'anode I'Ib is'connectedto one terminal of the-winding-IE andals'oto one=terminal of contact I3The second terminal of contact I3 is connected 'to bus bar III. Aresistor Isis-interposed between the cathode I! and the controlelectrode -I 7, and the control electrodel 1 is also connected throughacondenser 20 to the bus "bar I I. The cathode IB is connected to themovable" contact 2 I or a voltage divider 2|, which inturn 1s connectedacross the bus bars I0 and I I. The

control electrode I6 is connected tothebus bar" When the bus bars "areenergized and the field winding- I 2 of the 'motor -is excited, thepush'but ton'switch-id maybe'momentarily closed thereby completing acircuit from bus bar I0 through the contacts of the push buttonswitches-25 and 24 to and through thetenergizing winding I3 to busbarf'I I. Thereupon the switch I3 is energized to close theicontacts I3so that now the push but- 2 ton switch may beare1eased; -th'e winding 3re'-' maining energized. In responding, the switch [3 also closes thecontacts 13* and [3a Closure of contact 3 connects the motor armatureill to the bus bars i9 and ii in series with the resistor l4 and themotor begins to accelerate. Closure of contacts 13 connects the tube llacross the bus bars [6 and i i in series with the resistor 18.

Before closure of the contact l3 the potential of the cathode ll' andalso of the control electrode il was that of the bus bar H, and as nocurrent flowed through tube H the voltage drop contact 2 l in theresistors i8 and i5, and the potential across the condenser 29 werezero. At the instant When the contact 13 closes the tube ll becomesconducting, which produces a voltage drop across the resistors 18 andi9, resistor l9 producing a biasing potential of the control electrodeI! with respect to the cathode H This biasing potential controls theimpedance of the tube i1 and therefore the voltage drop through theresistor H3. The voltage drop across resistor it determines the finalchargin potential applied to the condenser 29, the rate of charge ofsaid condenser and the rate of rise of its potential being limited bythe resistor 59. As the charge of the condenser 52G :reases, thepotential of the control electrode ll becomes increasingly positive andthis in turn increases the current flowing through the resistor i8 andthe voltage drop therethrough. The voltage drop across the resistor itcontinues to exceed the voltage drop across condenser 2i] by an amountwhich is equal to that control electrode potential necessary to producethe voltage drop in the resistor it. This action in turn produces asubstantially linear rise of the potential or the condenser 28 and ofthe voltage drop across the resistor l8 and therefore of the potentialof the cathode ll.

The potential of the cathode H is impressed through the resistor 23 uponthe control electrode Et of the tube It. The potential of the controlelectrode iG with respect to the cathode 5 is controlled by adjustmentof the contact 2 i The adjustment is such that initially the potentialof the control electrode it prevents conduction of current by the tubei6. As the potential of the cathode ll rises, the potential of thecontrol electrode 55 rises correspondingly so that ultimately the tube56 becomes conducting, thereby energizing the relay winding i5sui'ficiently t0 aiiord closure of contacts to short circuit theresistor Hi, whereupon the motor will further accelerate to full speed.

The accompanying diagram (Fig. 2) illustrates the potential variationsjust discussed. Before closure of the contacts 53 the potential of thecathode Il is that of the negative bus bar ll. When the contacts itclose, the tube ['7 is conducting, as the potential of control electrodell is the same as that of the cathode i'i under which conditions thetube is slightly conducting. The tube current passing through theresistor 18 renders the cathode it positive, its potential suddenlyrising to the value A. The potential drop through resistor i5 isimpressed on the parallel circuit comprising the condenser 25 andresistor 55, the latter controlling the rate of charge of the condenser28. As a result the voltage of condenser 2d and with it the potential ofthe control electrode i'i rises linearly in accordance with the curve B.This in turn increases the conductivity of tube 17, thereby raising thepotential of the cathode li linearly as indicated by curve A. Thepotential of the cathode i'i is impressed through the resistor 23 andthe condenser 22 and the latter is charged exponentially at a very rapidrate. Thereafter its potential rises in accordance with the rise of therising potential impressed upon it by the resistor It as shown by curveC. As the potential of the condenser 22 is impressed on the controlelectrode It, the tube It ultimately becomes conducting to energize theswitch I 5 which short circuits resistor [4. The potential of thecathode I5 with respect to the control electrode l't may be varied byadjustment of the Thus the absolute potential of the control electrodei6 of the tube !6 affords energization of the switch i5 and thereforethe time interval between closure of contacts 13 and response of switchit may be varied.

It will be apparent that the linearly varying voltage of the condenser20, or the linearly varying potential of the cathode l'l may beimpressed upon circuits other than that shown to produce commutation ofsuch circuits after the lapse of a given time from the moment ofinitiation of conduction of the tube il. Furthermore, the tube it: maybe of other than the-gaseous type.

It will also be obvious that the system may be used to controlenergization of the switch [5 or some other translating device from acircuit in which the voltage is normally insuificient to actuate thedevice, but increases to a higher value, whereupon the response of thedevice to said higher value is delayed in the manner aforedescribed.

I claim:

1. A timing circuit comp-rising, in combination with a constantpotential unidirectional source oi current, a high vacuum tube having acathode,

an anode and a control electrode, a first resistor connecting saidcathode directly to said source, a second resistor connected to saidcathode, a condenser connected in series with said second resistor andtogether therewith in parallel with said first resistor, a connectionbetween the control electrode of said tube and the common terminal ofsaid second resistor and said condenser, a switch to control theconnection of said anode to said source, a second electron tube having acathode, an anode and a control electrode, means to impress the voltageof said source upon the main conducting path of said second tube, athird resistor connected to the cathode of the first mentioned tube, asecond condenser connected in series with said third resistor andtogether therewith in parallel with said first resistor, and aconnection between the control electrode of said second tube and thecommon terminal of said third resistor and said second condenser.

2. A timing circuit comprising, in combination with a constant potentialunidirectional source of current, a high vacuum tube having a cathode,an anode and a control electrode, a first resistor connecting saidcathode directly to said source a second resistor connected to saidcathode, a condenser connected in series with said second resistor andtogether therewith in parallel with said first resistor, a connectionbetween the control electrode of said tube and the common terminal ofsaid second resistor and said condenser, a switch to control theconnection of said anode to said source, a second electron tube having acathode, an anode and a control electrode, means nected in series withsaid third resistor and together in parallel with said first resistor,and a connection between the control electrode of said second tube andthe common terminal of said third resistor and said second condenser.

3. A timing circuit comprising, in combination with a constant potentialunidirectional source of current, a high vacuum tube having a cathode,an anode and a control electrode, a first resistor connecting saidcathode directly to said source, a second resistor connected to saidcathode, a condenser connected in series with said second resistor andtogether therewith in parallel with said first resistor, a connectionbetween the control electrode of said tube and the common terminal ofsaid second resistor and said condenser, a switch to control theconnection of said anode to said source, a second electron tube having acathode, an anode and a control electrode, means including a translatingdevice to connect the main conducting path of said second tube to saidsource and further including a voltage divider for varying the potentialimpressed on the cathode REFERENCES CITED The following references areof record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,052,183 Lewis et al Aug. 25,1936 2,129,036 Schlesinger Sept. 6, 1938 2,203,468 Martin June 4, 19402,279,007 Mortley Apr. 7, 1942 2,372,005 Kinsman Mar. 20, 1945 2,406,429Mahoney Aug. 27, 1946 2,495,919 Brunn Jan. 31, 1959

